<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>01_JS回顾</title>
</head>
<body>
    <script>
        var a=10;
        var b=10.11;
        var c="你好呀";
        var d='都好吗';
        var e=false;
        var f;
        console.log(a,typeof a);
        console.log(b,typeof b);
        console.log(c,typeof c);
        console.log(d,typeof d);
        console.log(e,typeof e);
        console.log(f,typeof f);

        let obj={};
        console.log(obj);
        obj.like="过年了";
        console.log(obj,typeof  obj,obj.like);

        let arr=[1,true,'hello'];
        console.log(arr,typeof arr);
        console.log(arr[0],arr[1],arr[2],arr[99]);

        console.log(Number('23'),typeof Number('23'));
        console.log(Number(true),typeof Number(true));
        console.log(Number('哈哈哈哈哈'),typeof Number('哈哈哈哈哈'));
        console.log(Number('7a'),typeof Number('7a'));

        console.log(0,Boolean(0));
        console.log(null,Boolean(null));
        console.log('',Boolean(''));
        console.log(NaN,Boolean(NaN));
        console.log(Boolean(undefined));
        console.log(Boolean(' '));
        console.log(Boolean('下午好'));
        console.log(Boolean(666));

    </script>
</body>
</html>